The present invention relates in general to the cleaning of webs in reproduction apparatus, and more particularly to a mechanism for cleaning the back side of a dielectric web in an electrostatographic reproduction apparatus.
In typical commercial reproduction apparatus (for example, electrostatographic copier/duplicators, printers, or the like), a latent image charge pattern is formed on a uniformly charged dielectric member. Pigmented marking particles are attracted to the latent image charge pattern to develop such image on the dielectric member. A receiver member is then brought into contact with the dielectric member, and an electric field applied to transfer the marking particle developed image to the receiver member from the dielectric member. After transfer, the receiver member bearing the transferred image is transported away from the dielectric member and the image is fixed to the receiver member by heat and/or pressure to form a permanent reproduction thereon.
One type of dielectric member typically utilized in the electrostatographic reproduction apparatus is a composite web having a base of flexible material. The web is entrained about a plurality of support rollers so as to form a closed loop path. The web is driven about the closed loop path to present particular areas of the web sequentially into association with electrographic process stations to form desired reproductions. It is common for airborne debris, such as marking particles and paper dust for example, to be attracted to, and collect on, the back side of the web. While this may not be of major consequence for dielectric support webs where the latent image charge patterns are formed from the front side of the web, it can cause undesirable image defects in the produced reproductions if the latent image charge patterns are formed from the back side of the web. Moreover, debris on the back side of the dielectric web may adversely effect performance of the web as it is driven about the closed loop path and, ultimately, overall performance of the reproduction apparatus.
Several mechanisms have been generally successfully employed for cleaning the back side of the dielectric support web of electrostatographic reproduction apparatus. One mechanism includes a stationary pad of a material, such as cotton for example. This pad can easily become saturated with debris; and, the period of time during which it takes for the pad to become saturated is not readily predictable. Saturation of the pad can cause excessive abrasion and scratching of the web. Therefore, the pad must be frequently inspected and cleaned.
Another mechanism for cleaning the back side of the dielectric web is shown in U.S. Pat. No. 4,853,741 (issued Aug. 1, 1989, in the name of Ku). The cleaning mechanism of the '741 patent utilizes an indexing web of material, such as a fabric of a nonwoven blend of polyester and rayon for example. The web is periodically indexed by a motor coupled to the mechanism. While this mechanism reduces the necessity for frequent inspection, as required with the stationary pad described above, it is of a more complex and expensive construction, requires a relatively more sophisticated control device, and takes up more space in the reproduction apparatus. It may also scratch the dielectric support web if it picks up any abrasive particles or debris.